1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having a switching element installed between a circuit and pads, a stacked module including the semiconductor device, a card including the semiconductor device, and a system which include the stacked module.
2. Description of the Related Art
To satisfy the high integration requirement of semiconductor products, a plurality of semiconductor devices can be stacked in chips or packages. In such a stacked structure, semiconductor devices can be individually selected, or when necessary, can be collectively selected. Chip selection signal lines can be disposed to be electrically coupled to the semiconductor devices respectively, and input/output (I/O) signals can be shared by the semiconductor devices.
For example, Japanese Patent Laid-Open Publication No. 2001-024151 discloses a semiconductor device with a plurality of stacked chips. The plurality of chips can be coupled through a top surface select pad, a bottom surface select pad, and vias. As another example, Japanese Patent Laid-Open Publication No. 2006-165073 discloses a method of stacking chips using a conductive paste burying a through hole formed in a silicon chip.
However, it is difficult to form a plurality of vias or to spread a plurality of conductive pastes on high-density semiconductor devices evenly without contacting other circuits. Particularly, allotting an additional area for connecting chip selection signal lines within the semiconductor devices negatively impacts the integration density of the semiconductor devices. Furthermore, achieving reliable insulation between the pads coupled to the chip selection signal line and other circuits is difficult.